http-push.c::add_send_request(): do not initialize transfer_request

http-push.c::add_send_request(): do not initialize transfer_request

That pointer will be assigned to new memory via

    request = xmalloc(sizeof(*request));

20 lines later unconditionally anyway, so it's safe to not assign it
to an arbitrary variable.

Signed-off-by: Stefan Beller <redacted>
Signed-off-by: Junio C Hamano <redacted>